And why we might never understand them

We exist in a sea of complex vibrations. Fortunately, over 600 million years of natural selection has helped wire up our 100 billion neurons to extract meaning from that sea. Although evolution gave us the tools to comprehend the world, it is unclear whether we have what it takes to understand how chemical reactions in the brain produce perception, sentience, and self-reflection. The weighty question that nags philosophers and neuroscientists alike is whether humans can ever solve the mind-body problem – how physical reality is translated by the brain into the conscious experience.

Dr. Colin McGinn, a philosopher of the mind at the University of Miami, has argued that the human brain is incapable of ever understanding the mind-body dichotomy. He explains that the problem can can be tackled in two ways, both of which are insufficient: “We can approach the problem either through introspection or through observation of the brain,” he says.

McGinn is quick to write off self-reflection as a possible path towards uniting the mind and the brain. “When you introspect on experiences it does not seem like the firing of neurons,” he says. Unaided, no inversion of the mind’s eye can reveal which part of the brain produces which mental state.

The other way of tackling the problem is to begin by observing the brain – scientists search for patterns of brain activity which correlate with conscious states. The literature is jam-packed with researchers looking for the neural firings which correlate to everything from sense of self to chocolate craving. The goal of this research is to eventually create models of how brains behave, and eventually explain how different states of mind come into being.

One such researcher is Dr. Adrian Owen, a professor of neuroscience at Cambridge University. His lab is trying to develop a “consciousness metre” to assess the level of awareness in coma patients. In his most recent research, conscious people and those in comas were asked to imagine performing a certain action, like playing tennis, while their brains were scanned in an fMRI – a massive magnet which measures brain activity. The patterns of brain activation were remarkably similar for both the conscious subjects and some of the coma patients, strongly suggesting that a certain percentage of coma patients maintain a degree of conscious awareness.

The question of how one can know the conscious state of anyone else is a central issue of the mind-body problem. Typically, we infer other people’s state of mind based on how their actions compare to our own – we could all empathize with Titanic’s Rose when her lover Jack sank to his icy death, because we compared her tears to our own tears, her contorted face with our own. In day-to-day life we relate people’s behaviour with their conscious states; true to this form, Dr. Owen and many other neuroscientists attempt to correlate people’s brain states with their conscious states.

He explains that his research “places the inference of conscious states at the level of brain activity rather than behavior.”

Yet Dr. Owen concedes that brain imaging has its limitations, because it doesn’t reveal how groups of neurons can contribute to the conscious experience. “All brain imaging can do is give correlations and not actually how some bit of the brain actually does a task,” he said.

McGinn agrees. “We need to discover the difference between correlation and causation. The correlations can be 100 per cent but this will not be an explanation for how the brain produces consciousness,” he said.

According to McGinn, to solve the mind-body problem we must revolutionize how we understand the mind and the brain. Sadly, he believes that, at this point in our evolutionary history, human beings aren’t up to the task. Right now we use perception to understand the brain and introspection to understand the mind; but to understand how the brain produces the mind, we need to explain both in the same terms. According to McGinn, this common currency cannot exist in the modern human brain.

But others disagree. Philosopher Dr. Daniel C. Dennett believes that an understanding of the mind and brain in a common currency could already exist, and that the currency may be mathematics.

“[McGinn’s idea of common currency] is in fact an excellent description of exactly the set of concepts that are being developed in cognitive science…and computational neuroscience,” Dr. Dennett argues.

Indeed, the fields of artificial intelligence and computational modelling appear to be moving toward a real solution to the mind-body problem. If scientists can make a computer model of the human brain – one that perfectly predicts conscious states from how a brain behaves – many people believe that the mind-body dichotomy could be revealed.

Progress toward such a model is already underway. Scientists at the University of Boston have created computer models which have successfully predicted human brain activity during a memory task. In New Mexico, scientists have simulated a brain consisting of 10 billion artificial neurons with 20 trillion connections, which – like any good nervous system – is designed for pattern recognition. Already a number of books have been published – perhaps prematurely – which offer mathematical models for the production of consciousness.

In a critique of Dr. McGinn, Dr. Dennett gives credit to computers for creating a medium in which both mind and brain can be expressed in the common language of math.

“Computer simulations…have expanded and disciplined our imaginations, dramatically enlarging the logical space of models that can be investigated,” he wrote.

Despite McGinn’s argument that “the perception of the colour red is not a mathematical state,” it seems quite possible that we will reach a point where brain imaging produces 100 per cent correlations with conscious states, and modelling produces a sophisticated set of mathematics to give meaning to these correlations. Whether or not this constitutes a solution to the mind-body problem remains to be seen.